Nonlinearities in cardiac electrophysiology and intracellular calcium dynamics, such as bifurcations, play a direct role in cardiac arrhythmogenesis, repolarization alternans, and pacemaker automaticity.
The dynamics of many cardiac arrhythmias, as well as the nature of transitions between different heart rhythms, have long been considered evidence of nonlinear phenomena playing a direct role in cardiac arrhythmogenesis. In most types of cardiac disease, the pathology develops slowly and gradually, often over many years. In contrast, arrhythmias often occur suddenly. In nonlinear systems, sudden changes in qualitative dynamics can, counterintuitively, result from a gradual change in a system parameter-this is known as a bifurcation. Here, we review how nonlinearities in cardiac electrophysiology influence normal and abnormal rhythms and how bifurcations change the dynamics. In particular, we focus on the many recent developments in computational modeling at the cellular level that are focused on intracellular calcium dynamics. We discuss two areas where recent experimental and modeling work has suggested the importance of nonlinearities in calcium dynamics: repolarization alternans and pacemaker cell automaticity.
Krogh‐Madsen et al. (Fri,) conducted a review in Cardiac arrhythmias. Nonlinear dynamics and computational modeling was evaluated. Nonlinearities in cardiac electrophysiology and intracellular calcium dynamics, such as bifurcations, play a direct role in cardiac arrhythmogenesis, repolarization alternans, and pacemaker automaticity.